Staff: Mentor

Energy is irrelevant. Light gives the same interference pattern no matter how dim it is.
What matters is whether we can detect it.
For the common source of gravity waves - inspiralling black holes - are there any directions of space into which gravity waves are not emitted, for reasons of symmetry?

Staff: Mentor

Unless you are extremely close to black holes in the merging process, you don't feel anything. The events detected by LIGO changed the lengths of the arms by 1 part in 10-21. If you are extremely close, it might feel like you are pushed/pulled a bit, but "from within".

Staff: Mentor

1 decibel is an odd value to choose, but whatever. It corresponds to about 20 µPa. No idea about Young's modulus for a human as a whole. Pick your favorite number. With the 14 GPa for the human bone listed there, we get 10-12 length changes. Most parts of the human are significantly softer and will deform more.

we get 10-12 length changes. Most parts of the human are significantly softer and will deform more.

The 10-21 stretch of gravity waves sounds like a small number, but the 10-12 stretch of 1 db sound also sounds like a small number.
Certainly 1 db sound at 250 Hz does not feel like "being pushed/pulled" - it is felt by ears alone.
So could sufficiently strong gravitational waves be perceived directly by naked ear as a quiet sound?

Good question and the interesting thing about gravitational waves is that they are a distortion of their medium so not only do they interfere by addition and subtraction but also by multiplication and exponentiation - amplitude and frequency modulation: two interacting gravitational waves will modulate each other's phases and their rates of change of phases.

10-12 is the stretch in bones, everything else will be stretched more, especially the eardrum.

I do not believe it works that way. If you stretch body parts using a force then the rigidity matters. The gravity wave is stretching space time. You would not feel anything. Soft tissues change in exactly the same way that hard tissues change.

The body parts would expand/shrink to their original size, assuming the frequency is low enough to make that possible. Different body parts would follow at different speed.

If you ride the vomit comet you perceive micro-gravity through one part of the cycle. At high altitude acceleration of earth's gravity is lower than at low altitude. The distortion of time-space changes but you feel the same micro-gravity. The bicep, humorous bone, and a measuring tape wrapped around the arm are all effected by dilation in the same way. [Tidal forces are different. Might make this example bad]

My understanding is that the laser light in the LIGO apparatus is the same frequency in both arms and at any point in the apparatus. The photons are arriving at the detector at different times. The arrival time depends on which leg they traveled and the amplitude of the gravity wave passing through the leg. The wavelength of the light is the same if measured at any point. So interactions between the light and matter will be the same. Particle-particle interactions are also the same anywhere in the LIGO apparatus. The observation of when two distant events occurred is effected by the gravity wave. The events themselves are not effected.

Staff: Mentor

Gravity waves passing through the galaxy would dissipate if energy was doing work on the molecules in objects.

Gravitational waves - gravity waves are something different.
Gravitational waves are doing an incredibly tiny amount of work on molecules.
What you cited is the LIGO situation - independent objects.
A human body doesn't consist of independent objects. If the distances within a solid object decrease in one direction and increase in another, it induces stress in the object.

If the distances within a solid object decrease in one direction and increase in another, it induces stress in the object.

If a 1 meter iron bar is clamped and tightened to 0.99 meters it is under stress. If the length of the space in the clamp and length of the iron bar are equal before, during, and after an event then there was no stress.